Studies of Iodine Metabolism in Hashimoto's Thyroiditis

Abstract

Nine patients with Hashimoto's thyroiditis, proven by needle biopsy and thyroid antibody tests, have been studied with respect to iodine metabolism. A variety of thyroid function tests were performed, including chromatographic analyses of thyroid biopsy tissue and serum. A number of alterations in intrathyroidal metabolism have been demonstrated, although such defects are not consistently present in each patient. These changes included: 1) a positive “flushing” test using potassium perchlorate, 2) an increased MIT/DIT ratio in the thyroid gland, 3) a decrease in the synthesis of thyroxine, 4) the production of a butanol-insoluble iodoprotein, 5) elevated PB131I, 6) the presence of circulating labeled iodotyrosines, and 7) the finding of a decreased thyroid MIT/DIT ratio with increased circulating triiodothyronine (in 1 case only). These various abnormalities are not specific for Hashimoto's disease, and probably represent the effects of thyroid gland injury on iodine metabolism.